How to Make It
Place porcini mushrooms in a medium bowl; cover with 2 cups boiling water. Cover and let stand 30 minutes or until tender. Drain in a sieve over a bowl, reserving soaking liquid. Thinly slice mushrooms.
Place each chicken breast half between 2 sheets of heavy-duty plastic wrap; pound to 1/2-inch thickness using a meat mallet or small heavy skillet. Sprinkle 1/4 teaspoon salt and black pepper over chicken. Heat a large stainless steel skillet over medium-high heat. Add 1 tablespoon oil to pan; swirl to coat. Add chicken; cook 3 minutes on each side or until browned and done. Remove chicken from pan; cover and keep warm.
Heat remaining 1 tablespoon oil in pan over medium-high heat. Add onion and garlic; sauté 2 minutes or until onion is lightly browned. Add remaining 1/2 teaspoon salt; porcini, shiitake, and button mushrooms; and oregano. Sauté 6 minutes or until mushrooms release moisture and darken. Sprinkle with flour; cook 1 minute, stirring constantly. Stir in stock, wine, and porcini soaking liquid; cook 3 minutes or until thickened, stirring frequently. Add chicken; cook 2 minutes or until heated, turning chicken once. Sprinkle with basil.